Plating for automotive part

ABSTRACT

A plated automotive part and method of plating are provided. One or more semi-bright finish layers of nickel are plated onto an automotive part. One or more bright finish layers of nickel are plated onto the outermost, semi-bright finish layer of nickel. One or more layers of a hard coat are plated onto the outermost, bright-finish layer of nickel. The hard coat has a pencil hardness of 4H or greater.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalPatent Application No. 60/561,531, filed Apr. 13, 2004, incorporated byreference herein.

BACKGROUND

The present invention relates to plated automotive parts and to methodsof plating automotive parts.

As shown in FIG. 1, some automotive parts 10 are conventionally formedof a base metal 12 (e.g., steel) to which one or more layers of nickel(i.e., “Ni”) 14 is/are applied. An outer layer 16 of chromium metal hasconventionally been applied to the layers 14 of Ni to complete theplating of the base metal 12.

FIG. 2 a details a conventional method of plating parts of the typeshown in FIG. 1 with chromium metal. Specifically, in step S1, a basemetal 12 is subjected to a pre-degreasing process. In step S2, the basemetal 12 is degreased. In step S3, the degreased base metal 12 issubjected to water washing (one or more times). In step S4, the washedbase metal 12 is subjected to acid cleaning (i.e., pickling). In stepS5, the base metal 12 is again subjected to water washing (one or moretimes). In step S6, a semi-bright finish layer 14A of Ni is plated ontothe base metal 12. The once-plated base metal 12 is then allowed to cool(i.e., recover) in step S7. In step S8, a bright finish layer 14B of Niis plated onto the semi-bright layer 14A of Ni. In step S9, thetwice-plated base metal 12 is again allowed to recover. In step S10,chromium activation occurs. In step S11, an outer layer 16 of chromiummetal is plated onto the bright finish layer 14B of Ni. In step S12, theplated base metal 12 is again allowed to recover. In step S13, theplated base metal 12 is subjected to water washing (one or more times).Finally, in step S14, the plated base metal 12 is subjected to hot waterwashing.

The chrome plating gives the automotive part an attractive appearanceand protects the part from scratches and rust because chromium metal hasa high surface hardness and excellent wear and corrosion resistance.Additionally, when chromium metal is used to plate an automotive partsuch as a seatbelt tongue, use of chromium metal ensures easy fasteningand releasing of the buckle and reliable latching due to the highsurface hardness and excellent wear and corrosion resistance.

However, the chromium plating process requires the use of hexavalentchromium. Hexavalent chromium is a specified toxic substance, and itsuse requires treatment of wastewater and exhaust air to removehexavalent chromium. Thus, manufacturers using hexavalent chromium mustinvest in, operate, and maintain a detoxification system and must payadditional costs to meet local regulatory requirements.

FIG. 2 b details a conventional method of detoxifying wastewater andexhaust air generated during the process shown in FIG. 2. Specifically,in step S101 (which occurs during and/or after steps S1 to S5 in FIG. 2a), wastewater is treated to remove or neutralize alkali and acid. Instep S102 (which occurs during and/or after steps S6 to S9 in FIG. 2 a),wastewater is treated to remove or neutralize Ni. In step S103 (whichoccurs during step S11 of FIG. 2 a), exhaust air is treated to removehexavalent chromium by capturing hexavalent chromium mist released intothe atmosphere during chromium plating and depositing the capturedhexavalent chromium in the wastewater. In step S104 (which occurs duringand/or after steps S10 to S14 in FIG. 2 a), wastewater is treated by areduction treatment of hexavalent chromium to trivalent chromium.Finally, is step S105 (which occurs after step S104), other chromium istreated.

Even when the detoxification treatment is strictly managed, the use ofhexavalent chromium presents environmental and safety risks. Such risksinclude leakage of hexavalent chromium from the manufacturing processpotentially resulting in air, soil, and/or water contamination andadherence of hexavalent chromium to products potentially creatingadverse health effects in persons exposed to the hexavalent chromium.

Additionally, manufacturers desiring to use hexavalent chromium mustsatisfy local regulatory requirements and obtain approval and licensingto use hexavalent chromium. Obtaining approval and licensing can be alengthy process and, in some cases, approval may be impossible toobtain. Even if approval is obtained, risks to the manufacturer includeproduction stoppages due to releases of hexavalent chromium,compensation paid to parties injured by hexavalent chromiumcontamination, and the cost of environmental cleanup due to hexavalentchromium pollution.

Thus, although chrome has proven to be an effective plating material,its use raises environmental concerns. What is needed, therefore, is anautomotive plating and method of plating which, like chrome, provideseffective plating properties but which is more environmentally friendlythan chrome.

SUMMARY

According to an embodiment of the invention, a plated automotive partand method of plating are provided. One or more semi-bright finishlayers of nickel may be plated onto an automotive part. One or morebright finish layers of nickel may be plated onto the outermost,semi-bright finish layer of nickel. One or more layers of a hard coatmay be plated onto the outermost, bright-finish layer of nickel.According to a preferred embodiment, the hard coat has a pencil hardnessof 4H or greater.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory only,and are not restrictive of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the presentinvention will become apparent from the following description, appendedclaims, and the accompanying exemplary embodiments shown in thedrawings, which are briefly described below.

FIG. 1 is a cross-sectional view of an automotive part covered with aconventional plating material;

FIG. 2 a is a block diagram of a conventional plating method;

FIG. 2 b is a block diagram of a conventional wastewater and exhaust airtreatment method;

FIG. 3 a is a cross-sectional view of an automotive part covered with aplating material according to an embodiment of the present invention;

FIG. 3 b is a cross-sectional view of an automotive part covered with aplating material according to an embodiment of the present invention;

FIG. 4 a is a block diagram of a plating method according to anembodiment of the present invention;

FIG. 4 b is a block diagram of a wastewater treatment method accordingto an embodiment of the present invention; and

FIG. 5 is a perspective view of an embodiment of a plated automotivepart according to the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention will be described below withreference to FIGS. 3 a-5.

As shown in FIG. 3 a, an automotive part 110 includes a base metal 12(e.g., steel) onto which one or more layers 14 of Ni are applied.Moreover, although only two under layers 14 of Ni are shown, theinvention contemplates plated parts and methods of plating involving anynumber of layers 14 of Ni. Regardless of the number of layers 14 of Ni,the outermost layer 14 of Ni is coated with a final layer 18, which is ahard coat layer.

The hard coat layer 18 may be clear so that the automotive part 110 hasa metallic appearance of Ni. The hard coat layer 18 may have a pencilhardness of about 4H or greater and a thickness D1 of about 1 μm orgreater. For example, the thickness D1 may be about 5 μm or greater. Thehard coat layer 18 may comprise, for example, a material such as epoxy,acrylic, polyester, urethane, or melamine alkyl. The hard coat materialaccording to the present invention is a more environmentally friendlymaterial than conventional chromium plating material.

According to an embodiment of the invention, the thickness D1 of theouter layer 18 is about 6 μm or greater, and the outer layer 18 has apencil hardness of about 4H or greater. In addition, although only oneouter layer 18 is contemplated in this embodiment, more than one layermay be appropriate for some applications and are, therefore, fullywithin the scope of the invention.

According to another embodiment, the outer layer 18 is an inorganic hardcoat layer such as, for example, an Si—R linked siloxane of a siliconecontaining compound as described in Japanese Patent Application No.JP2004-501233, incorporated by reference herein. In this embodiment, theouter layer 18 may have a pencil hardness of about 7H or greater and athickness D1 of about 1 μm or greater.

According to another embodiment of the invention, the outer layer 18 ofan automotive part 210 includes a first layer 18A of the hard coat and asecond layer 18B of the hard coat, as shown in FIG. 3 b. The first layer18A may have a thickness D2 of about 5 μm or greater, and the secondlayer 18B may have a thickness D3 of about 6 μm or greater.Additionally, the first layer 18A may have a pencil hardness of about HBor greater, and the second layer 18B may have a pencil hardness of about4H or greater.

According to an embodiment, after the hard coat layer 18 is applied, thelayer 18 is cured using a curing process that may include application ofone or more of the following: (a) ultraviolet light; (b) heat; (c) farinfrared radiation; and/or (d) near infrared radiation to the automotivepart.

FIG. 4 a details a method of plating automotive parts of the type shownin FIG. 3 according to an embodiment of the present invention.Specifically, in step S1, a base metal 12 is subjected to apre-degreasing process. In step S2, the base metal 12 is degreased. Instep S3, the degreased base metal 12 is subjected to water washing (oneor more times). The base metal 12 is preferably water washed two times.In step S4, the washed base metal 12 is subjected to acid cleaning(i.e., pickling). In step S5, the base metal 12 is again subjected towater washing (one or more times). The base metal 12 is preferablysubjected to water washing two times. In step S6, a semi-bright finishlayer 14A of Ni is plated onto the base metal 12. The once-plated basemetal 12 is then allowed to cool (i.e., recover) in step S7. In step S8,a bright finish layer 14B of Ni is plated onto the semi-bright layer 14Aof Ni. In step S9, the twice-plated base metal 12 is again allowed torecover. In step S13, the plated base metal 12 is subjected to waterwashing (one or more times). The plated base metal 12 is preferablysubjected to water washing two times. In step S14, the plated base metal12 is subjected to hot water washing.

Each of the above-described steps is similar to corresponding steps ofthe conventional method shown in FIG. 2 a. However, the presentinvention eliminates steps S10, S11, and S12, which involve chromiumactivation, chromium plating, and recovery of the chromium plated basemetal 12. According to this embodiment, after step S14, the surface ofthe twice-plated base metal 12 is adjusted in step S15. In step S16, thehard coat layer 18 is applied. Finally, in step S17, the hard coat layer18 is cured.

It should be recognized, as indicated by dashed lines in FIG. 4 a, insome embodiments of the method, after step S7, the method may return tostep S6. In these method embodiments, one or more additional layers 14Aof semi-bright finish Ni may be added to the first layer 14A ofsemi-bright finish Ni originally applied in step S6 by successivelyrepeating steps S6 and S7. Upon adding a satisfactory number ofsemi-bright finish layers 14A of Ni, these method embodiments continueat step S8.

Similarly, as indicated by dashed lines in FIG. 4 a, in some embodimentsof the method, after step S9, the method may return to step S8. In thesemethod embodiments, one or more additional layers 14B of bright finishNi may be added to the first layer 14B of bright finish Ni originallyapplied in step S8 by successively repeating steps S8 and S9. Uponadding a satisfactory number of bright finish layers 14B of Ni, thesemethod embodiments continue at step S13.

Finally, as indicated by dashed lines in FIG. 4 a, in some embodimentsof the method, after step S17, the method may return to step S16. Inthese method embodiments, one or more additional layers 18 of the hardcoat may be added to the first layer 18 of hard coat originally appliedin step S16 by successively repeating steps S16 and S17. Upon adding asatisfactory number of hard coat layers 18, these method embodimentsstop after step S17.

FIG. 4 b details a method of treating wastewater according to anembodiment of the present invention. Specifically, in step S101 (whichpreferably occurs during and/or after steps S1 to S5 in FIG. 4 a),wastewater is treated to remove or neutralize alkali and acid. In stepS102 (which occurs during and/or after steps S6 to S9 in FIG. 4 a),wastewater is treated to remove or neutralize Ni.

Each of the above-described steps is similar to corresponding steps ofthe conventional method shown in FIG. 2 b. However, the presentinvention eliminates step S103 of the conventional method, whichinvolves capturing hexavalent chromium mist released into the atmosphereduring chromium plating; eliminates step S104 of the conventionalmethod, which involves wastewater reduction treatment of hexavalentchromium to trivalent chromium; and eliminates step S104 of theconventional method, which involves treatment of other chromium.

In an automotive part plated according to the method embodimentsdescribed above, the hard coat layer 18 may have a lower hardness andpoorer wear resistance than conventional chromium plating. Thus,according to an embodiment of the present invention, the plated part maybe protected from wear by minimizing the friction against the surface ofthe plated part. To protect the plated part (e.g., a seatbelt tongue),components in frictional contact with the plated part (e.g., a base anda latch of a seatbelt buckle) may include a coating containingmolybdenum disulfide or fluorocarbon resin powder or may be treated withmanganese phosphate plating or zinc plating having lower hardness thanthat of the alloy plating.

FIG. 5 shows an automotive part 30 plated pursuant to the methoddescribed in FIG. 4 a. The automotive part 30 may be, for example, aseatbelt tongue. However, the present invention is not limited to suchtongues. Rather, the invention applies to any automotive part including,but not limited to, a seat belt buckle, a D-ring, a ball (which is partof a vehicle sensor mounted in a seat belt retractor), and other relatedautomotive parts. Other automotive parts may also be plated, forexample, parts used in airbag devices, seat weight sensors, and belttension sensors may be plated according to the present invention.Further by way of example, a child seat and a steering wheel may beplated.

Thus, according to embodiments of the present invention, the use of aspecified toxic substance in the plating of automotive parts iseliminated so that environmental protection and human safety isimproved, wastewater and exhaust air treatment is improved, andmanufacturing cost is reduced.

Given the disclosure of the present invention, one versed in the artwould appreciate that there may be other embodiments and modificationswithin the scope and spirit of the invention. Accordingly, allmodifications attainable by one versed in the art from the presentdisclosure within the scope and spirit of the present invention are tobe included as further embodiments of the present invention. The scopeof the present invention is to be defined as set forth in the followingclaims.

1-49. (canceled)
 50. A plated automotive part comprising: a base metal;a Ni layer on the base metal; and an outermost plating layer including ahard coat, wherein the outermost plating layer has a pencil hardness of4H or greater.
 51. The part of claim 50, wherein the outermost platinglayer comprises epoxy.
 52. The part of claim 50, wherein the outermostplating layer comprises acrylic.
 53. The part of claim 50, wherein theoutermost plating layer comprises polyester.
 54. The part of claim 50,wherein the outermost plating layer comprises urethane.
 55. The part ofclaim 50, wherein the outermost plating layer comprises melamine alkyl.56. The part of claim 50, wherein the outermost plating layer comprisesan Si-R linked siloxane of a silicone containing compound.
 57. The partof claim 50, wherein the Ni layer includes a semi-bright finish layerdirectly on the base metal.
 58. The part of claim 57, wherein the Nilayer includes a bright finish layer overlying the semi-bright finishlayer.
 59. The part of claim 50, wherein the outermost plating layer isclear.
 60. The part of claim 50, wherein the outermost plating layercomprises an inorganic hard coat.
 61. The part of claim 60, wherein theoutermost plating layer has a thickness of about 1 μm or greater and apencil hardness of about 7H or greater.
 62. The part of claim 50,wherein a thickness of the outermost plating layer is about 6 μm orgreater.
 63. The part of claim 50, wherein the outermost plating layerincludes a first outermost plating layer and a second outermost platinglayer, and wherein the first outermost plating layer has a thickness ofabout 5 μm or greater and the second outermost platinf layer has athickness of about 6 μm or greater.
 64. The part of claim 63, whereinthe first outermost plating layer has a pencil hardness of about HB orgreater and the second outermost plating layer has a pencil hardness ofabout 4H or greater.
 65. The part of claim 50, wherein the platedautomotive part is configured to engage a corresponding automotive part,and wherein a surface of the corresponding automotive part configured tocontact the plated automotive part has a hardness lower than the harnessof the outermost plating layer of the plated automotive part.
 66. Thepart of claim 65, wherein the surface of the corresponding automotivepart includes a coating containing molybdenum disulfide.
 67. The part ofclaim 65, wherein the surface of the corresponding automotive partincludes a coating containing fluorocarbon resin powder.
 68. The part ofclaim 65, wherein the surface of the corresponding automotive partincludes a manganese phosphate plating.
 69. The part of claim 65,wherein the surface of the corresponding automotive part includes a zincplating.
 70. A seat belt tongue comprising an outermost plating layerincluding a hard coat having a pencil hardness of 4H or greater.
 71. Thetongue of claim 70, wherein the outermost plating layer comprises epoxy.72. The tongue of claim 70, wherein the outermost plating layercomprises acrylic.
 73. The tongue of claim 70, wherein the outermostplating layer comprises polyester.
 74. The tongue of claim 70, whereinthe outermost plating layer comprises urethane.
 75. The tongue of claim70, wherein the outermost plating layer comprises melamine alkyl. 76.The tongue of claim 70, wherein the outermost plating layer comprises anSi—R linked siloxane of a silicone containing compound.
 77. The tongueof claim 70, wherein a thickness of the outermost plating layer is about5 μm.
 78. The tongue of claim 70, wherein the outermost plating layeroverlies at least one Ni layer.
 79. The tongue of claim 70, wherein theoutermost plating layer is clear.
 80. The tongue of claim 70, whereinthe outermost plating layer comprises an inorganic hard coat.
 81. Thetongue of claim 80, wherein the outermost plating layer has a thicknessof about 1 μm or greater and a pencil hardness of about 7H or greater.82. The tongue of claim 70, wherein a thickness of the outermost platinglayer is about 6 μm or greater.
 83. The tongue of claim 70, wherein theoutermost plating layer includes a first outermost plating layer and asecond outermost plating layer, and wherein the first outermost platinglayer has a thickness of about 5 μm or greater and the second outermostplating layer has a thickness of about 6 μm or greater.
 84. The tongueof claim 83, wherein the first outermost plating layer has a pencilhardness of about HB or greater.
 85. The tongue of claim 83, wherein thesecond outermost plating layer has a pencil hardness of about 4H orgreater.
 86. The tongue of claim 70, wherein the tongue is configured toengage a seat belt buckle having a base and a latch, and wherein ahardness of a surface of the base and a hardness of a surface of thelatch are lower than the harness of the outermost plating.
 87. Thetongue of claim 86, wherein the surfaces of the base and the latchinclude a coating containing molybdenum disulfide.
 88. The tongue ofclaim 86, wherein the surfaces of the base and the latch include acoating containing fluorocarbon resin powder.
 89. The tongue of claim86, wherein the surfaces of the base and the latch include a manganesephosphate plating.
 90. The tongue of claim 86, wherein the surfaces ofthe base and the latch include a zinc plating.